tx_read_only

Description

tx_read_only specifies whether a transaction is read-only.

Privilege requirements

• Query variables

  • Global level

    sys tenant and all user tenants can execute the SHOW VARIABLES statement or query the SYS.TENANT_VIRTUAL_GLOBAL_VARIABLE view (Oracle mode) or the information_schema.GLOBAL_VARIABLES view (MySQL mode) to view the value of a global system variable.

  • Session level

    sys tenant and all user tenants can execute the SHOW VARIABLES statement or query the SYS.TENANT_VIRTUAL_SESSION_VARIABLE view (Oracle mode) or the information_schema.SESSION_VARIABLES view (MySQL mode) to view the value of a session system variable.

• Modify variables

  • Global level

    • sys tenant can modify the value of a global system variable.

    • MySQL user tenants must have the SUPER or ALTER SYSTEM privilege to modify the value of a global system variable.

    • Oracle user tenants must have the ALTER SYSTEM privilege to modify the value of a global system variable.

  • Session level

    sys tenant and all user tenants can modify the value of a session system variable.

Attributes

Usage

After you set the tx_read_only variable:

• If the variable takes effect at the session level, it affects only the current user.

• If the variable takes effect at the global level, it affects all users who connect to the database after the variable is set.

Examples

Set the transaction to a read-only transaction.

• Session level

  obclient> SET tx_read_only = 1;
  

• Global level

  obclient> SET GLOBAL tx_read_only = 1;